The invention relates to an electrochemical gas sensor in a closed casing with gas openings for measuring gases in gas mixtures.
A variety of methods are known for measuring the concentration of individual gases in gas mixtures. For example, DE-B 1190698 discloses a method for the determination of hydrogen or oxygen in a gas mixture, in which the gas mixture is fed through the gas space of a gas diffusion electrode, and the electrode potential and electrode current are then measured to determine the concentration of the gas. By way of example, this document also indicates that several gases, such as hydrogen and oxygen, can be determined in tandem by using one diffusion electrode each for hydrogen and oxygen, by feeding the gas mixture first to the oxygen electrode which ignores hydrogen, and then to the hydrogen electrode.
The document Journal of Power Sources 34 (1991), pages 331-338, A. Winsel and C. Fischer, xe2x80x9cNew apparatus for the measurement of the selfdischarge of the nickel hydroxide electrodexe2x80x9d discloses a method for determining oxygen content by means of a zinc-air cell.
WO 97/35186 also discloses a method and a device for determining oxygen concentration, in which a zinc-air cell is used as the measuring element.
Thus, an object of the invention is to determine the concentration of two gas components in a gas mixture, and to provide a suitable gas sensor which is simple and compact in design and operates reliably.
In the invention, a single electrochemical cell is used for measuring two gas components in a gas flow. For example, oxygen and hydrogen or oxygen and nitrous oxide can be measured in a gas flow. The electrochemical gas sensor can, therefore, be employed in conjunction with an anesthetizing device, to measure oxygen concentrations and nitrous oxide concentrations, or may be used at the output of methanol reformers to measure nitrogen and oxygen content.